The present invention relates to a silver halide photographic light-sensitive material. In particular, the present invention relates to an ultrahigh contrast negative type photographic light-sensitive material suitable as a silver halide photographic light-sensitive material used for a photomechanical process. The present invention also relates to a method for development of a silver halide photographic light-sensitive material.
In photomechanical processes used in the field of graphic arts, used is a method in which photographic images of continuous tone are converted into so-called dot images in which variable image density is represented by sizes of dot areas, and such images are combined with photographed images of characters or line originals to produce printing plates. For silver halide photographic light-sensitive materials used for such a purpose, ultrahigh contrast photographic characteristic enabling clear distinction between image portions and non-image portions has been required in order to obtain favorable reproducibility of characters, line originals and dot images.
As a system responding to such a requirement of ultrahigh contrast photographic characteristic, there has been known the so-called lithographic development method in which a silver halide light-sensitive material comprising silver chlorobromide is treated with a hydroquinone developer having an extremely low effective concentration of sulfite ions to obtain images of high contrast. However, in this method, the developer is extremely unstable against oxidation by air since the sulfite ion concentration in the developer is extremely low, and therefore a lot of developer must be replenished in order to stably maintain the developer activity.
As image forming systems in which the instability of the image formation according to the lithographic development method is eliminated and light-sensitive materials are processed with a developer showing good storage stability to obtain ultrahigh contrast photographic characteristic, there can be mentioned those described in, for example, U.S. Pat. Nos. 4,166,742, 4,168,977, 4,221,857, 4,224,401, 4,243,739, 4,269,922, 4,272,606, 4,311,781, 4,332,878, 4,618,574, 4,634,661, 4,681,836, 5,650,746 and so forth. These are systems in which a silver halide photographic light-sensitive material of surface latent image type containing a hydrazine compound is processed with a developer containing hydropuinone/metol or hydroquinone/phenidone as main developing agents and 0.15 mol/l or more of sulfite preservative and having pH of 11.0-12.3 to form ultrahigh contrast negative images having a gamma of 10 or higher. According to these systems, photographic characteristics of ultrahigh contrast and high sensitivity can be obtained, and because sulfite can be added to the developer at a high concentration, stability of the developer to air oxidation is markedly improved compared with the conventional lithographic developers.
In order to form sufficiently ultrahigh contrast images with use of a hydrazine compound, it is necessary to perform processing with a developer having pH of 11 or higher, usually 11.5 or higher. Although it becomes possible to increase the stability of the developer by use of a sulfite preservative at a high concentration, it is necessary to use such a developer of high pH as described above in order to obtain ultrahigh contrast photographic images, and the developer is likely to suffer from air oxidation and instable even with the presence of the preservative. Therefore, various attempts have been made in order to realize ultrahigh images with a lower pH to further improve stability of the developer.
For example, U.S. Pat. No. 4,269,929 (Japanese Patent Laid-open Publication (Kokai, henceforth referred to as xe2x80x9cJP-Axe2x80x9d) No. 61-267759), U.S. Pat. No. 4,737,452 (JP-A-60-179734), U.S. Pat. Nos. 5,104,769, 4,798,780, JP-A-1-179939, JP-A-1-179940, U.S. Pat. Nos. 4,998,604, 4,994,365 and JP-A-8-272023 disclose methods of using a highly active hydrazine compound and a nucleation accelerator in order to obtain ultrahigh images by using a developer having pH of less than 11.0.
However, silver halide photographic light-sensitive materials used for such image-forming Systems have a problem concerning processing stability such as fluctuation of sensitivity caused by change of activities of the hydrazine compound and the nucleation accelerator due to exhaustion of processing solutions. As means for improving processing stability, use of an emulsion providing higher contrast can be mentioned. However, it has a problem that use of an emulsion providing higher contrast results in reduction of sensitivity. Therefore, it has been desired to develop a technique that can provide high sensitivity and superior processing stability.
Considering these problems of the conventional techniques, an object of the present invention is to provide a silver halide photographic light-sensitive material that provides high contrast, high sensitivity and favorable processing stability. Another object of the present invention is to provide a development method for use in processing of a light-sensitive material providing high contrast images in an automatic developing machine, which shows little fluctuation of photographic performance and no silver staining during running even with a small replenishing amount of a developer.
As a result of various researches of the inventors of the present invention, it was found that the aforementioned objects could be achieved by a silver halide photographic light-sensitive material defined in the following (1) to (4).
(1) A silver halide photographic light-sensitive material comprising at least one silver halide emulsion layer on a support, wherein the silver halide emulsion layer contains silver halide containing a metal complex having a cyanide ligand, and the silver halide photographic light-sensitive material contains a hydrazine compound having an onium group in the molecule.
(2) A silver halide photographic light-sensitive material comprising at least one silver halide emulsion layer on a support, wherein the silver halide emulsion layer contains silver halide containing a Group VIII metal compound, and the silver halide photographic light-sensitive material contains a hydrazine compound having an onium group in the molecule represented by the following formula (1):
Formula (1) 
wherein R1 represents an arylene group or a divalent heterocyclic group, Q represents an onium group, J represents a divalent bridging group, xe2x80x94G1xe2x80x94R2 represents xe2x80x94COCF2H or xe2x80x94COCF2CF2COOM, where M represents a hydrogen atom or a counter cation, and both of A1 and A2 represent a hydrogen atom, or one of them represents a hydrogen atom, and the other represents an acyl group, a sulfonyl group or an oxalyl group.
(3) A monochromatic silver halide photographic light-sensitive material which is developed with a developer having a pH of 9.0-11.0 and a replenishing amount of 330 mL/m2 or less for the developer, wherein the monochromatic silver halide photographic light-sensitive material has one or more hydrophilic colloid layers on a support, at least one of the hydrophilic colloid layers is a silver halide emulsion layer, and the monochromatic silver halide photographic light-sensitive material contains at least one kind of a hydrazine compound having an onium group in the molecule.
(4) A monochromatic silver halide photographic light-sensitive material which is developed with a developer having a pH of 9.0-11.0, wherein the monochromatic silver halide photographic light-sensitive material has one or more hydrophilic colloid layers on a support, at least one of the hydrophilic colloid layers is a silver halide emulsion layer, and the monochromatic silver halide photographic light-sensitive material contains at least one kind of a hydrazine compound having an onium group in the molecule represented by the following formula (1):
Formula (1) 
wherein R1 represents an arylene group or a divalent heterocyclic group, Q represents an onium group, J represents a divalent bridging group, xe2x80x94G1xe2x80x94R2 represents xe2x80x94COCF2H or xe2x80x94COCF2CF2COOM, where M represents a hydrogen atom or a counter cation, and both of A1 and A2 represent a hydrogen atom, or one of them represents a hydrogen atom, and the other represents an acyl group, a sulfonyl group or an oxalyl group.
The hydrazine compound having an onium group in the molecule used in the present invention is preferably a compound represented by the following formula (1-a) or (1-b):
Formula (1-a) 
Formula (1-b) 
wherein xe2x80x94G1xe2x80x94R2 represents xe2x80x94COCF2H or xe2x80x94COCF2CF2COOM, where M represents a hydrogen atom or a counter cation, J represents an alkylene group, and Q represents a pyridinium group or a quinolinium group.
The present invention also provides a method for development of silver halide photographic light-sensitive material, which comprises developing the aforementioned silver halide photographic light-sensitive material with a developer having a pH of 9.0-11.0. In the development method of the present invention, the developer is preferably replenished in an amount of 330 mL/m2 or less.